Filters employing permanent magnets as the filter medium are prevalent in the prior art. Exemplary magnetic filtering devices as described for instance in U.S. Pat. No. 2,789,655 to Michael et al., U.S. Pat. No. 3,139,403 to Cramer et al., U.S. Pat. No. 5,043,063 to Latimer, and GB 850,233 typically enclose the magnets in fixed rods or columns that are secured permanently to the housing and are difficult to service. Some filtration devices are augmented with filter screens to remove sludge as disclosed in U.S. Pat. No. 4,946,589 to Hayes. Internal sprayers are often required to clean and removed the contaminants as shown in U.S. Pat. No. 6,077,333 to Wolfs. Recently, U.S. Pat. No. 6,730,217 to Schaaf el al. disclose a magnetic filter with a removable magnetic core assembly which consists of permanent magnet bars carried within non-magnetic insulation tubes.
A major drawback of current magnetic filtration apparatuses is that they are difficult to service in part because in many instances the entire core assembly containing all the permanent magnet bars and the protective tubes must be removed from the filter housing simultaneously. In other configurations, all the magnet bars must to be withdrawn together from all the tubes since the individual insulation tubes are inaccessible. As a result, it is inconvenient and expensive to replace the magnet bars or insulation tubes, and in extreme cases a whole core assembly must to be replaced just to service one or a few un-repairable magnet bars and/or tubes. Power equipment or mechanical tools are required for the operation due to the weight of the core assembly. Another deficiency is that the number of insulating tubes in the filtration device tends to be fixed and cannot be adjusted as needed.